The present disclosure relates to the subject matter contained in Japanese Patent Application Nos. 2002-156538, 2002-156539 and 2002-156542 all filed May 30, 2002, which are incorporated herein by reference in their entireties.
1. Field of the Invention
The present invention relates to a suspension in a vehicle, particularly to an independent suspension of a laterally mounted leaf spring type for independently suspending wheels on both sides of the vehicle by using a leaf spring provided along the vehicle width direction.
2. Background Art
An example of a conventional suspension having a leaf spring in a vehicle width direction is described in JP-UM-A-6-79609. The suspension includes a single leaf spring made of synthetic resin disposed along the vehicle width direction and coil springs arranged respectively on left and right sides of a vehicle. When the coil springs are also used in addition to the leaf spring in this way in order to apply to a truck having a large carrying capacity, there arise problems as follows. In addition to an increase in the cost due to the coil spring, it is necessary to secure a space for installing the coil springs respectively on the left and right sides of the vehicle. Further, man-hours for assembling the left and right coil springs to the vehicle increases.
Therefore, there is requested an independent suspension which can dispense with a coil spring by sufficiently ensuring spring rigidity of the suspension by laminating two sheets of leaf springs and which is excellent in durability.
It is an object of the invention to provide an independent suspension which can sufficiently ensure spring rigidity of the suspension by using two sheets of laminated leaf springs and which is excellent in durability.
The invention provides a suspension including: wheel supporting members for supporting left and right wheels respectively on a vehicle body movably in vertical direction; a first leaf spring extending along a vehicle width direction on a lower side of the vehicle body and having both end portions each disposed on an upper side one of the wheel supporting members; a second leaf spring disposed between the first leaf spring and the vehicle body and extending along the first leaf spring; a pivot projected from a lower face of the vehicle body and supporting a middle portion in the vehicle width direction of the second leaf spring on the vehicle body; a spacer provided between the second leaf spring and the first leaf spring in the vicinity of the pivot; sliders fixed on lower faces of both end portions of the second leaf spring and brought into slidable contact with upper faces of the both end portions of the first leaf spring; and receiving pieces interposed between the both end portions and the wheel supporting members respectively; wherein each of the wheel supporting members includes a recess portion opened upwardly on which the receiving pieces is mounted to be prevent from detachment; each of the receiving pieces includes an engaging portion for engaging with one of the both end portions of the first and second leaf springs; and each of the receiving pieces includes an elastic member capable of deforming to follow a displacement of a relative position between the first leaf spring and one of the wheel supporting members in the vehicle width direction.
Therefore, as a result of attaching the first leaf spring and the second leaf spring to the vehicle in this way, when load from the wheel supporting member is inputted to the both end portions of the two leaf springs, the two leaf springs can be bent taking the pivot and the spacer arranged in the vicinity thereof as a fulcrum. Thus, the wheels can elastically be suspended from the vehicle body.
Further, when the first leaf spring and the second leaf spring are bent, a relative displacement is brought about in the vehicle width direction between the both end portions of the two leaf springs. However, it is possible to transmit only a load in a vertical direction from the both end portions of the second leaf spring to the both end portions of the first leaf spring without producing substantially any load in the vehicle width direction.
Further, when the first leaf spring and the second leaf spring are bent, a relative displacement occurs in the vehicle width direction between the first leaf spring and the wheel supporting member. However, since the elastic members of the receiving pieces are deformed to respectively follow the relative displacement in the vehicle width direction between the both end portions of the first leaf spring and the wheel supporting members, occurrence of friction between the both end portions of the first leaf spring and the wheel supporting members can be prevented.
Preferably, one of the second leaf spring and the slider engaged therewith includes a projection extending in the vertical direction. The other of the second leaf spring and the slider engaged therewith includes a hole portion for receiving the projection. The engaging portions of the receiving pieces are hole portions into which the both end portions of the first leaf spring and the second leaf spring can be inserted along with the sliders.
Therefore, the slider can be locked on the second leaf spring by using a simple structure of fitting the projection into the hole portion. In a state of assembling the slider between the first and the second leaf springs in this way, by inserting the both end portions of the first and the second leaf springs respectively into the hole portions of the receiving pieces along with the sliders, a leaf spring assembly can be formed before integrating it to the vehicle. Therefore, the man-hour for assembling can be reduced.
Preferably, the first and the second leaf springs are formed so that widths of the both end portions in the front and rear direction of the vehicle are narrowed toward outer sides in the vehicle width direction. The engaging portion of each of the receiving pieces is an erected wall disposed along one end portions of the first and second leaf springs. The slider includes a flange portion extending at least in downward from an end edge thereof, the end edge extending along the vehicle width direction, the flange portion capable of sliding along a sidewall of the recess portion.
Therefore, when the both end portions of the second leaf spring are displaced relative to the receiving pieces outward in the vehicle width direction, the both end portions are brought into contact with the erected walls of the receiving pieces. Further, when the both end portions of the second leaf spring are displaced relative to the receiving pieces inward in the vehicle width direction, the flange portions of the slider fixed to the one end portion of the second leaf spring can slide along the first leaf spring and along the sidewall of the recess portion. Thus, detachment of the second leaf spring can be prevented.
Further, by assembling the slider between the first and second leaf springs, mutual position shift between the first and second leaf springs is restricted. Therefore, operations of inserting the both end portions of the first and second leaf springs into the hole portions of the receiving pieces along with the slider is facilitated.
Preferably, the spacer includes: a metal plate adhered to the second leaf spring; and an elastic member made of rubber connected to the metal plate by vulcanizing adherence and brought into contact with the first leaf spring.
Thus, the metal plate of the spacer is firmly fixed to the second leaf spring by using the adhesive and the elastic body made of rubber is solidly fixed to the metal plate by using vulcanizing adherence. Therefore, the spacer can be made more undetachably. Further, since the metal plate is adhered to the leaf spring on the upper side which is a tension face, adhesive force of the adhesive can be maintained favorably.
There arises a problem in which strength of the leaf spring is deteriorated due to high temperature in the case where the elastic member made of rubber is directly adhered to the leaf spring by vulcanization. However, according to the structure, such a problem can be avoided.